Abrasive disc support



p 12, 1967 J. w. PURCELL, JR 3,340,652

ABRAS IVE DIS C SUPPORT Filed Feb; 1, 1965 I n vemar,

Joseph M Puree/(Jr B, 626., 9.3.3:?

, I/forney United States Patent 3,340,652 ABRASIVE DISC SUPPORT JosephW. Purcell, Jr., Los Angeles, Calif., assignor to Merit Products, Inc.,Los Angeles, Calif., a corporation of California Filed Feb. 1, 1965,Ser. No. 429,361 6 Claims. (Cl. 51-376) This invention relates to anabrasive disc support or back-up pad.

The type of disc support to which this invention relates comprises acircular body member which is customarily formed of resilient materialmolded on a flat circular piece of fabric. The resilient material iscustomarily molded around and bonded to a central core or hub. The hubcarries means for securing the disc support to an arbor for rotation andmay also carry means for removably holding a circular disc of abrasivematerial.

Devices of this type which are now in use have a structural weakness inthat during rotation and flexing of the disc support in use, theresilient material along the fiat portion of the disc support directlyadjacent to the hub tends to separate from the hub. This is generallythe weakest part of the structure because of the difficulty of bondingelastomeric material to metal.

It is accordingly the primary object of the present invention to providean improved abrasive disc support of the type described.

In essence, my invention contemplates strengthening the weak area wherethe resilient material is joined to the hub by providing the fabric witha plurality of slits rather than a central circular opening. The slittedportion is then bent upwardly to form a plurality of segments whichextend along the outer wall of the hub. An annular ring is then mountedaround the segments to hold them in position and the elastomericmaterial is then molded around the entire assembly.

The resulting abrasive disc support is substantially stronger thanconventional disc supports because the fabric segments and ring act toprevent separation of the elastomeric material from the hub. The discsupport is thus stronger and will last substantially longer in use thandevices made in the conventional manner.

It is accordingly among the objects of my invention to provide a novelabrasive disc support having all of the advantages and benefits of thestructure set forth above and described in further detail hereinafter inthis specification.

My invention also comprises such other objects, advantages andcapabilities as will later more fully appear and which are inherentlypossessed by my invention.

While I have shown in the accompanying drawings a preferred embodimentof my invention, it should be understood that the sarne is susceptibleof modification and change without departing from the spirit of myinvention.

Referring to the drawings,

FIG. 1 is a side elevational view of an abrasive disc supportconstructed in accordance with my invention;

FIG. 2 is a sectional view of the same, taken along line 22 of FIG. 1;

FIG. 3 is an exploded perspective view showing the annular ring, slittedfabric base and hub prior to assembly;

FIG. 4 is a perspective view showing the annular ring, fabric base andhub after assembly and prior to molding.

A preferred embodiment and method which have been selected to illustratemy invention comprise forming an abrasive disc support from a hub 10,which is customarily formed of metal or other substantially rigidmaterial. The hub generally incorporates holding means 11 at one endthereof for removably holding a circular sheet of abrasive material. Thehub 10 also provides means for mount- 3,34%,652 Patented Sept. 12, 1967ing the disc support on an arbor 12 which is in turn connected to asuitable source of rotation.

The hub 10 is provided with an outer wall having a narrow substantiallycylindrical lower portion 13 and a larger substantially frusto-conicalupper portion 14. The entire outer wall of the hub 10 may be coated witha suitable composition which acts to improve its bond with theelastomeric material.

The resilient portion of the disc support is preferably formed around acircular base 15, which customarily comprises a circular piece of nylonfabric or other suitable material. Instead of providing a circularopening at the center of the base 15 which fits around the hub 10, Iprovided the base 15 with a plurality of slits 20, as shown in FIG. 3 ofthe drawings, which extend radially outwardly from the center asuflicient distance to permit the hub 10 to fit within the slittedportion.

The hub 10 is then inserted through the central slitted portion of thebase 15, so that the slitted portion forms a plurality of segments 16which extend along and directly adjacent to the lower portion 13 and thelower part of the upper portion 14 of the outer wall of the hub 10.

An annular retainer ring 17, which is preferably formed of metal orother substantially rigid material, is then mounted over the baseportions of the segments 16. The ring 17 is substantially concentricwith and spaced slightly from the cylindrical lower portion 13 of thehub 10, with the base portions of the segments 16 being securely heldtherebetween.

The retainer ring 17 and the base '15 may also be coated or impregnatedwith a suitable composition of the type known to the art for improvingthe bond between them and the elastomeric compound.

The assembly described, which is shown in FIG. 4 of the drawings, isthen placed in a mold and the elastomeric compound is molded around itand bonded to it in order to form a complete abrasive disc support asshown in FIG. 1 of the drawings. The resulting disc support or back-uppad is somewhat resilient and is adapted to support a disc of abrasivematerial for grinding and polishing fiat or slightly contoured surfaces.

The elastomeric compound permeates and becomes bonded to the base 15,forming a thin layer on one side of the base and a much thicker layer onthe opposite side of the base. The elastomeric material forms aresilient pad 19, which surrounds the hub 10 and is bonded to the ring17, the segments 16 and the upper portion 14 of the outer wall of thehub 10.

It will be noted that separation of the pad 19 from the hub 10 isprevented by the segments 16 and retainer ring 17, which strengthen theformerly weak portion of the assembly and provide a longer useful lifefor the disc support.

I claim:

1. An abrasive disc support comprising a substantially rigid hub, saidhub having an outer wall, a circular base having a plurality of segmentsadjacent its center, said hub being disposed adjacent the center of saidbase, with said segments extending along the outer wall of said hub, aretainer ring disposed around said hub, said segments being held betweensaid retainer ring and the outer wall of said hub, and elastomericmaterial bonded to said base, retainer ring and the outer wall of saidhub.

2. An abrasive disc support comprising a substantially rigid hub, saidhub having an outer wall, a circular base cut adjacent its center toprovide a plurality of integral segments, said hub being disposed withinthe center of said base, with said segments extending along the outerwall of said hub, an annular retainer ring disposed concentricallyaround said hub, said segments being held between said ring and theouter wall of said hub, and elastoneric material bonded to said base,retainer ring and the outer wall of said hub.

3. An abrasive disc support comprising a substantially rigid hub, saidhub having an outer wall, said outer wall having a substantiallycylindrical portion, a circular fabric base slitted adjacent its centerto provide a plurality of integral triangular segments, said hub beingdisposed within the center of said base, With said segments extendingalong the cylindrical portion of the outer wall of said hub, an annularretainer ring disposed concentrically around the cylindrical portion ofthe outer wall of said hub, said segments being held between said ringand the cylindrical portion of the outer wall of said hub, andelastomeric material forming a resilient pad bonded to said base,retainer ring and the outer wall of said hub.

4. An abrasive disc support comprising a hub, said hub having an outerwall, a base substantially surrounding said hub, said base having aplurality of segments extending along the outer wall of said hub, aretainer ring disposed around said segments and holding said segmentsadjacent to the outer wall of said hub, and elastomeric material bondedto said base, retainer ring and the outer wall of said hub.

5. An abrasive disc support comprising a hub, said hub having an outerwall, a base substantially surrounding said hub, said base having anintegral portion extending along the outer wall of said hub, retainingmeans disposed around and holding said integral portion adjacent to theouter wall of said hub, and elastomeric material bonded to said base andthe outer wall of said hub.

6. An abrasive disc support comprising a hub, said hub having an outerWall, a base having a portion thereof extending along the outer wall ofsaid hub, and elastomeric material bonded to said base and the outerwall of said hub.

References Cited UNITED STATES PATENTS 250,003 11/1881 Rogers 51379407,248 7/1889 Rogers 51401 3,119,208 1/ 1964 Gianatasio 51-4053,166,877 1/1965 Reames 51378 3,239,971 3/1966 Freerks 51-379 ROBERT C.RIORDON, Primary Examiner.

D. G. KELLY, Assistant Examiner.

1. AN ABRASIVE DISC SUPPORT COMPRISING A SUBSTANTIALLY RIGID HUB, SAIDHUB HAVING AN OUTER WALL, A CIRCULAR BASE HAVING A PLURALITY OF SEGMENTSADJACENT ITS CENTER, SAID HUB BEING DISPOSED ADJACENT THE CENTER OF SAIDBASE, WITH SAID SEGMENTS EXTENDING ALONG THE OUTER WALL OF SAID HUB, ARETAINER RING DISPOSED AROUND SAID HUB, SAID SEGMENTS BEING HELD BETWEENSAID RETAINER RING AND THE OUTER WALL OF SAID HUB, AND ELASTOMERICMATERIAL BONDED TO SAID BASE, RETAINER RING AND THE OUTER WALL OF SAIDHUB.